Here is a knife that I designed for cutting folded paper on a flat surface.  So, you can use it to cut gift wrap or other paper to size on a table or floor.  It's just the right sharpness to cut light paper and doesn't have a point so that you don't accidentally hurt yourself.  

I used to use a real knife to cut gift wrap, but it was too sharp and wouldn't pull the paper tight so you didn't get a straight line.  Alternatively, I used to use a credit card, but it was too dull, and sometimes the paper would tear.  This however is just right to cut a straight line without tearing the paper.  Also, the handle is designed so that you can hold it with your fingers while laying it flat on a surface.

I've used it for many years.  I don't know why I never posted it to printables, but now it can be in a contest.  It works great!

I made this model using Solidworks.